JP2010159729A - Blowby gas reducing device for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a blowby gas reducing device for an internal combustion engine which can suppress the deterioration of fuel economy at high altitude. <P>SOLUTION: The blowby gas reducing device 60 comprises an electronic control type PCV valve 63 for adjusting a flow rate of blowby gas flowing from a crankcase 22 to an intake passage 49 containing a throttle valve 45, and an electronic control device 70 for controlling an opening of the PCV valve 63. The electronic control device 70 is set to reduce the opening of the PCV valve 63 with respect to an opening of the throttle valve 45 as the atmospheric pressure decreases under an idling state while controlling the opening of the PCV valve 63 on the basis of the atmospheric pressure. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a blow-by gas reduction device for an internal combustion engine that includes an electronically controlled PCV valve that controls the flow rate of blow-by gas flowing from a crankcase to an intake passage, and a control device that controls the opening degree of the PCV valve.

  As a conventional blow-by gas reduction device, a mechanical PCV (Positive Crankcase Ventilation) valve that adjusts a gas flow rate according to a negative pressure in an intake passage of an internal combustion engine is provided. This PCV valve reciprocates a valve element housed in a case by the interaction between a spring attached to the valve element and a negative pressure, thereby causing a gas flow path formed between the case and the valve element. By enlarging and reducing, the flow rate of the gas passing through the PCV valve (hereinafter simply referred to as “PCV flow rate”) is adjusted (see, for example, Patent Document 1).

  The opening degree of the mechanical PCV valve is designed to improve the ventilation of the engine body at the medium vehicle speed, that is, at the medium vehicle speed (for example, 50 km / h) of the intake passage. Is set in advance so that the PCV flow rate to be supplied is relatively large.

JP 2007-231785 A

  By the way, since the atmospheric pressure in the high altitude (for example, 2000 m above sea level) is lower than the atmospheric pressure on the flat land (for example at an altitude of 0 m), the flow rate of the gas introduced into the intake passage decreases. Therefore, for example, the throttle opening of the throttle valve when the internal combustion engine is idling at high altitude is larger than the throttle opening when the internal combustion engine is idling on a flat ground. Specifically, the throttle opening degree when the internal combustion engine is idling at high altitude corresponds to the throttle opening degree when the vehicle is steady running at a medium vehicle speed on a flat ground. As a result, the PCV flow rate when the internal combustion engine is idling at high altitude is greater than that during idling operation on flat ground, and corresponds to the PCV flow when traveling at medium vehicle speed on flat ground. As a result, the amount of gas supplied to the combustion chamber increases, so the fuel injection amount also increases to maintain the stoichiometric air-fuel ratio. As a result, the fuel efficiency deteriorates at high altitudes.

  However, in an engine-type PCV valve, its opening degree is uniquely changed according to the difference between the pressure of the engine body and the pressure of the intake passage. Cannot be suppressed.

  This invention is made | formed in view of such a situation, The objective is to provide the blow-by gas reduction apparatus of the internal combustion engine which can suppress the deterioration of a fuel consumption in the case of a highland.

In the following, means for achieving the above object and its effects are described.
(1) The invention according to claim 1 is an electronically controlled PCV valve that controls the flow rate of blow-by gas flowing from a crankcase to an intake passage provided with a throttle valve, and a control that controls the opening degree of the PCV valve. In the blow-by gas reduction device for an internal combustion engine comprising the device, the control device controls the opening degree of the PCV valve based on atmospheric pressure, and the control device reduces the atmospheric pressure in an idle operation state. Accordingly, the gist is to set the opening of the PCV valve to be smaller than the opening of the throttle valve.

  According to this invention, since the opening degree of the PCV valve is set smaller than the opening degree of the throttle valve at a high altitude where the atmospheric pressure is lower than the flat ground, an increase in the PCV flow rate can be suppressed. Therefore, it becomes possible to suppress deterioration in fuel consumption due to an increase in fuel injection amount accompanying an increase in PCV flow rate.

The schematic diagram which shows the structure of the engine about embodiment which implemented the blow-by gas reduction apparatus of the internal combustion engine of this invention. The graph which shows the relationship between the PCV flow volume and throttle opening in a flat ground and a highland about the blow-by gas reduction apparatus of the internal combustion engine of the embodiment. The flowchart which shows the process sequence about "PCV valve | bulb control processing" performed by the electronic controller in the embodiment.

With reference to FIGS. 1-3, one Embodiment which actualized the blow-by gas reduction apparatus of the internal combustion engine concerning this invention is described.
As shown in FIG. 1, an engine 10 includes an engine main body 20 for generating power through combustion of a mixture of air and fuel, an intake device 40 for taking external air into the engine main body 20, and an engine main body. A fuel supply device for supplying fuel to the combustion chamber 31 in the engine 20, a blow-by gas reduction device 60 for supplying blow-by gas in the engine body 20 to the intake device 40, and an electronic device that controls these devices in an integrated manner. And a control device 70.

  The engine body 20 stores a cylinder block 21 for burning the air-fuel mixture in the combustion chamber 31, a crankcase 22 for supporting the crankshaft 26 in cooperation with the cylinder block 21, and engine oil. The oil pan 23, a cylinder head 24 for arranging valve-operated parts, and a head cover 25 for suppressing scattering of engine oil to the outside. A crank chamber 32 formed by the cylinder block 21 and the crankcase 22 and a valve operating chamber 33 formed by the cylinder head 24 and the head cover 25 are connected by a communication chamber 34 formed in the cylinder block 21. .

  The intake device 40 has an air intake 41 for taking outside air into the device, and an air cleaner 42 for catching foreign matter in the air taken in via the air intake 41 (hereinafter referred to as “new air”). A throttle body 44 for adjusting the flow rate of fresh air through opening and closing of the throttle valve 45, an intake hose 43 connecting the intake downstream side of the air cleaner 42 and the intake upstream side of the throttle body 44, and the intake air of the throttle body 44 The intake manifold 46 is connected to the downstream side and the intake upstream side of the cylinder head 24. The intake manifold 46 includes a surge tank 47 for retaining fresh air that has passed through the throttle body 44 and a plurality of sub-pipes 48 for sending fresh air in the surge tank 47 to the intake ports of the cylinder head 24. Is provided. That is, in the intake device 40, intake air is taken in through the passage in the air intake 41, the passage in the air cleaner 42, the passage in the intake hose 43, the passage in the throttle body 44, and the passage in the intake manifold 46. An intake passage 49 for feeding into the engine body 20 is formed. The intake manifold 46 is provided with an injector 50 that injects fuel into the intake passage 49.

  The blow-by gas reducing device 60 has a function of supplying blow-by gas flowing out from the combustion chamber 31 into the crank chamber 32 to the intake downstream side of the throttle valve 45 in the intake device 40, and the intake air purified by the air cleaner 42. 40 is configured as a device having a function of supplying the crank chamber 32 from the upstream side of the intake of the throttle valve 45 in the engine 40 and a function of adjusting the flow rate of blow-by gas supplied from the engine body 20 to the intake device 40.

  Specifically, a first ventilation passage 61 formed in a manner of connecting the head cover 25 and the surge tank 47 as a passage for sending blow-by gas in the crank chamber 32 from the valve operating chamber 33 into the surge tank 47. Is provided. Further, the head cover 25 and the intake hose 43 are used as a passage for sending fresh air in the intake hose 43 into the valve operating chamber 33 or as a passage for sending blow-by gas into the intake hose 43 from the valve operating chamber 33. A second ventilation passage 62 formed in a connecting manner is provided. Further, as a valve for adjusting the flow rate of the gas containing blow-by gas flowing from the valve operating chamber 33 toward the surge tank 47, an electronic device provided on the head cover 25 to change the passage area of the first ventilation passage 61 is provided. A control type PCV valve 63 is provided.

  Here, under the same engine operating condition, as the opening degree of the PCV valve 63 increases, blow-by gas, which is a gas passing through the PCV valve 63 supplied from the valve operating chamber 33 into the surge tank 47, and The flow rate of the air-fuel mixture consisting of fresh air (hereinafter simply referred to as “PCV flow rate”) is increased. That is, the PCV flow rate is controlled by the opening degree of the PCV valve 63.

  The electronic control device 70 is provided with a rotation sensor 71, a throttle sensor 72, and a PCV valve sensor 73. The rotation sensor 71 is provided in the vicinity of the crankshaft 26 of the engine body 20 and outputs a signal corresponding to the rotation speed of the crankshaft 26. The throttle sensor 72 is provided in the vicinity of the throttle valve 45 and outputs a signal corresponding to the throttle opening of the throttle valve 45. The PCV valve sensor 73 is provided in the vicinity of the PCV valve 63 and outputs a signal corresponding to the opening of the PCV valve.

Next, a control mode of the PCV flow rate with respect to the throttle opening of the throttle valve 45 will be described with reference to FIG.
The electronic control unit 70 basically sets a required value of the PCV flow rate corresponding to the throttle opening of the throttle valve 45 based on the curves G1 and G2 of FIG. 2, and sets the actual PCV flow rate to the set required value. Therefore, the opening degree of the PCV valve 63 is adjusted. Here, the curve G1 is a control curve for the PCV flow rate on flat ground (altitude 0 m), and the curve G2 is a control curve for the PCV flow rate on high altitude (altitude 2000 m). Hereinafter, the control mode of the PCV flow rate based on the curves G1 and G2 will be described in detail.

First, the control mode of the PCV flow rate based on the curve G1 will be described.
In the case where the throttle opening is small, that is, the throttle opening T1, the required value of the PCV flow rate is larger than “0” and the minimum value within the change range of the required value (hereinafter referred to as “required value PA”). Is set. The throttle opening T1 corresponds to the throttle opening during idle operation.

  Further, in the region from the throttle opening T1 to the throttle opening T2, the required value of the PCV flow rate is set larger as the throttle opening increases. The throttle opening T4 corresponds to the throttle opening when the vehicle is traveling normally at a medium vehicle speed (for example, 50 km / h).

  In the region from the throttle opening T2 to the throttle opening T3, the required value of the PCV flow rate is the maximum value (hereinafter referred to as “required value PB”) within the change range of the required value, or a value in the vicinity thereof. Set to Here, in the same region, the actual PCV flow rate on the side with the smaller throttle opening is substantially the required value PB. On the other hand, in the same region, the actual PCV flow rate in the region with the larger throttle opening is indicated by a one-dot chain line in FIG. 2 because the pressure in the intake passage 49 and the pressure in the crank chamber 32 are substantially equal. Thus, it rapidly decreases as the throttle opening increases, and eventually the PCV flow rate becomes “0” or a value in the vicinity thereof. Then, the PCV flow rate decreases most at the throttle opening T3.

  Next, the control mode of the PCV valve 63 based on the curve G2 will be described. Here, the curve G2 is substantially the same as the curve G1, and in the following, only different parts of the curve G1 and the curve G2 will be described, and description of other parts will be omitted.

  In the curve G2, the required value of the PCV flow rate is set to the required value PA at the throttle opening T4. That is, at the throttle opening T4, the opening of the PCV valve 63 relative to the throttle opening of the throttle valve 45 is set to be smaller than the curve G1.

  Further, in the region from the throttle opening T4 to the throttle opening T2, the required value of the PCV flow rate is set larger as the throttle opening increases. Also in this region, the opening degree of the PCV valve 63 relative to the throttle opening degree is set to be smaller than the curve G1. The region from the throttle opening T2 to the throttle opening T3 is the same as the curve G1. The actual PCV flow rate is also the same.

  In the graph of FIG. 2, the engine load at the throttle opening T1 is a low load, and the engine load in the region from the throttle opening T1 to the throttle opening T2 corresponds to the middle engine load region, and the throttle opening. The engine load in the region from the degree T2 to the throttle opening T3 corresponds to a high engine load region.

  By the way, in idling operation at high altitude, the throttle opening is larger than idling operation on flat ground, and is approximately the same as throttle opening T4, which is one of the throttle opening at medium vehicle speed on flat ground. Become. That is, as shown in the graph of FIG. 2, the throttle opening during flat idling is the throttle opening T1, whereas the throttle opening during high altitude idling is the throttle opening T4.

  Here, in this high altitude idling state, the PCV flow rate is set to a value (hereinafter referred to as “required value PC”) corresponding to the throttle opening T4 of the curve G1 which is a control curve of the PCV flow rate on the flat ground. Then, the amount of gas supplied to the combustion chamber 31 also increases due to the increase in the PCV flow rate accompanying this. At this time, in response to a change in the air-fuel ratio due to an increase in the gas amount, correction is performed to increase the fuel injection amount by air-fuel ratio control, resulting in a deterioration in fuel consumption.

  Therefore, since the blow-by gas reduction device 60 of the present embodiment has a control curve for the PCV flow rate at high altitude, the required value PC for the PCV flow rate corresponds to the throttle opening T4 when the idling operation is at high altitude. Instead of this, the required value PA during idle operation, which is a smaller value than this, is used. As a result, the actual PCV flow rate is prevented from greatly exceeding the required value during idle operation.

  Next, with reference to FIG. 3, the process procedure of the “PCV valve control process” executed by the electronic control unit 70 in order to realize the above-described adjustment of the PCV flow rate will be described. The process is repeatedly executed at predetermined calculation cycles while the engine 10 is in operation.

  In the PCV valve process, first, in step S10, the atmospheric pressure is estimated. Specifically, on the basis of the throttle opening of the throttle valve 45 with respect to a predetermined rotation speed and load on a flat ground, the actual throttle opening at the same rotation speed and load is compared, and the change in atmospheric pressure from the change amount Estimate the amount. Specifically, first, data on the amount of change in the throttle opening with respect to the rotation speed and load based on the change in atmospheric pressure is created in advance. Next, based on the data, it is calculated which atmospheric pressure corresponds to the actual amount of change of the throttle opening relative to the throttle opening on the flat ground. Here, the actual throttle opening is obtained by the throttle sensor 72. Further, the load can be obtained based on at least one of the intake air amount passing through the throttle valve 45 and the fuel injection amount.

  Next, in step S11, it is determined whether the atmospheric pressure is 850 hPa or less. This atmospheric pressure corresponds to an atmospheric pressure at an altitude of 2000 m. If it is determined that the atmospheric pressure is greater than 850 hPa (NO in step S11), the PCV flow rate control curve is set to the curve G1 in step S12. On the other hand, when it is determined that the atmospheric pressure is 850 hPa or less (YES in step S11), in step S13, the PCV flow rate control curve is set to the curve G2. As described above, the PCV flow rate control suitable for the flatland and the highland is realized by changing the control curve of the PCV flowrate in the flatland and the highland.

[Effect of the embodiment]
According to the blow-by gas reduction device 60 of the present embodiment, the following effects can be achieved.

  (1) In the present embodiment, the electronic control unit 70 sets the opening degree of the PCV valve 63 to be smaller than the opening degree of the throttle valve 45 as the atmospheric pressure decreases in the idle state. Thereby, the increase in the PCV flow rate can be suppressed in the highland where the atmospheric pressure is lowered. Therefore, it becomes possible to suppress deterioration in fuel consumption due to an increase in fuel injection amount accompanying an increase in PCV flow rate.

  (2) In the present embodiment, the electronic control unit 70 controls the PCV flow rate by the control curves G1 and G2 of the PCV flow rate according to the case of the flat ground and the highland. As a result, it is possible to supply a PCV flow rate that is suitable when the vehicle performs idle operation on a flat ground and a highland.

  (3) In the present embodiment, the atmospheric pressure is estimated from the throttle opening with respect to a predetermined rotation speed and load. This eliminates the need for a new sensor for estimating or measuring the atmospheric pressure, thereby reducing the number of components.

(Other embodiments)
In addition, the said embodiment can also be changed and implemented as shown, for example below.
In the blow-by gas reduction device 60 of the present embodiment, the atmospheric pressure is estimated by the throttle opening with respect to a predetermined rotation speed and load, but the configuration for estimating the atmospheric pressure is limited to this. There is no. For example, the atmospheric pressure may be estimated by an atmospheric pressure sensor mounted on a car navigation system or the like.

  In the blow-by gas reduction device 60 of the present embodiment, the atmospheric pressure is 850 hPa as a threshold, and the curves G1 and G2 that are PCV flow rate control curves are selected. However, the atmospheric pressure threshold is limited to this. There is nothing. Other values may be used as the atmospheric pressure threshold.

  In the blow-by gas reduction device 60 of the present embodiment, two types of curves G1 and G2 are used as PCV flow rate control curves, but the number of control curves is not limited to this. For example, three or more types of curves may be used.

  In the blowby gas reduction device 60 of the present embodiment, both the first ventilation passage 61 and the second ventilation passage 62 are connected to the head cover 25, but the connection positions of the first ventilation passage 61 and the second ventilation passage 62 are It is not limited to this. For example, the first ventilation passage 61 and the second ventilation passage 62 may be connected to the crank chamber 32 as long as the structure can reduce the blow-by gas from the engine body 20 to the upstream side and the downstream side of the throttle valve 45. .

  DESCRIPTION OF SYMBOLS 10 ... Engine (internal combustion engine), 20 ... Engine main body (engine main body), 21 ... Cylinder block, 22 ... Crankcase, 23 ... Oil pan, 24 ... Cylinder head, 25 ... Head cover, 26 ... Crankshaft, 31 ... Combustion chamber 32 ... Crank chamber, 33 ... Valve chamber, 34 ... Communication chamber, 40 ... Intake device, 41 ... Air intake, 42 ... Air cleaner, 43 ... Intake hose, 44 ... Throttle body, 45 ... Throttle valve, 46 ... Intake manifold , 47 ... Surge tank, 48 ... Sub pipe, 49 ... Intake passage, 50 ... Injector, 60 ... Blow-by gas reduction device, 61 ... First ventilation passage, 62 ... Second ventilation passage, 63 ... PCV valve, 70 ... Electronic control device (Control means) 71 ... rotation sensor 72 ... throttle sensor 73 ... PCV valve Capacitors.

Claims (1)

In a blow-by gas reduction device for an internal combustion engine, comprising an electronically controlled PCV valve that controls the flow rate of blow-by gas flowing from a crankcase to an intake passage provided with a throttle valve, and a control device that controls the opening degree of the PCV valve ,
The control device controls the opening of the PCV valve based on atmospheric pressure,
The blow-by gas reduction device for an internal combustion engine, wherein the control device sets the opening of the PCV valve relative to the opening of the throttle valve as the atmospheric pressure decreases in an idle operation state. .

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